Organizations on the Enterprise plan can limit how long their members are signed into Threads for across desktop and mobile devices. If a session timeout is set for an organization, each person will need to sign back into Threads when they hit their session time limit.
Once the time limit is reached for a session, all clients that use that session will be forced to re-sign into Threads if any action is taken on the client. This means that if someone has 3 tabs open to Threads that use the same session, all three of those tabs would timeout once the session expires.
The session timeout will apply to all clients including mobile apps, but mobile clients with an expired session will still receive push notifications. Tapping on a notification will take the person to a sign-in screen on their phone.
Learn how to set a session timeout for your organization.